Key: 1.Bf1 b3 [1…Bf4 2.e4! (thr. 3.Be2#) cxb2 3. Sf5 (zz) b3 4.d4 (zz) cxd4 5.S5xd4 any 6.Be2# 4…Bd2/Bc1/Bg5/Bh6 5.Sg3 any 6.Be2#] 2.Rd2+ cxd2 3.Sf5 (thr. 4.Se3#) Bf4 4.e4 (zz) b2 5.d4 (zz) Bg5/Bh6 6.Sg3 any 7.Be2# 5...cxd4 6.S5xd4 any 7.Be2#
Sacrifice. Zugzwang.
